U.S. Pat. Nos. 4,122,110 and 4,291,126 and the French patent application Nos. 2,523,957 and 2,564,091, corresponding to U.S. patent application Ser. No. 478,764 filed on Mar. 25, 1983 and Ser. No. 732,488 filed on May 10, 1985, have disclosed catalysts used in a process for manufacturing an alcohol mixture from CO, H.sub.2 or CO, CO.sub.2, H.sub.2 mixtures. These catalysts generally have a good selectivity in the conversion of carbon oxides and hydrogen to alcohols and their selectivity to saturated linear primary alcohols of 2 or more carbon atoms is often higher than 70% by weight. Finally they have a high initial productivity, mostly higher than or equal to about 0.1 ton on alcohols per ton of catalyst and per hour.
These catalysts usually comprise at least three essential elements: copper, cobalt and at least one alkali and/or alkaline earth metal.
The catalysts disclosed in U.S. Pat. No. 4,122,110 further contain at least one metal M selected from the group formed of chromium, iron, vanadium and manganese and optionally zinc, and/or magnesia and/or an aluminous cement.
The catalysts disclosed in U.S. Pat. No. 4,291,126 contain, in addition to the elements mentioned for the catalysts disclosed in U.S. Pat. No. 4,122,110, at least one metal from the group of rare earths having atomic numbers from 57 to 71 inclusive, and optionally at least one additional noble metal from group VIII of the periodic classification of elements (Handbook of Chemistry and Physics 37.sup.th edition 1955-1956 p. 392-393).
The catalysts disclosed in the French patent application No. 2,523,957 contain, in addition to the above-mentioned essential elements, alumina and optionally zinc, at least one metal M selected from the group formed of manganese, vanadium, iron and rhenium, at least one metal N selected from the group formed of scandium, yttrium, thorium, zirconium and rare earth metals of atomic numbers from 57 to 71 inclusive, chromium and at least one noble metal from group VIII of the periodic classification of elements.
The catalysts disclosed in the above-mentioned documents contain the mentioned metal elements in well defined weight proportions and atomic ratios.
The European patent application No. 110,357 discloses catalysts containing at least four elements in their formula, such for example as:
Copper, nickel, at least one alkali and/or alkaline-earth metal and at least one metal from groups II.sub.A, III.sub.A, IV.sub.A, II.sub.B, III.sub.B, IV.sub.B and the fourth period of groups V.sub.B, VI.sub.B, and VII.sub.B of the periodic classification of elements; or PA0 zinc, at least one compound selected from the group formed of iron, cobalt and nickel, at least one alkali and/or alkaline earth metal and at least one metal from groups II.sub.A, III.sub.A, IV.sub.A, II.sub.B, III.sub.B, IV.sub.B and the fourth period of groups V.sub.B, VI.sub.B, VII.sub.B of periodic classification of elements. PA0 Relatively high amounts of hydrocarbons are produced together with the alcohols. PA0 When contacted with the synthesis gas, the above-mentioned catalysts may generate a transitory methanation reaction, highly exothermic, which requires the progressive substitution of the synthesis gas for the inert gas introduced in the unit before admission of the synthesis gas (after reduction with hydrogen and before admission of the synthesis gas). PA0 In the presence of the above-mentioned metal elements, the thermal stabilization of the copper-cobalt pair generally requires the addition of a high proportion of alkali metals, generally resulting in a reduced purity of the produced alcohol mixture. PA0 For all these reasons, the procedures of conditioning the catalyst under hydrogen and/or reactive gases are generally complex, (French patent 2 593 957 and French patent application filed on May 17, 1985 under No. 85 07 581, corresponding to the U.S. application Ser. No. 863,283, filed on May 15, 1986) and make the use of the above-mentioned catalysts difficult.
U.S. Pat. No. 4,440,668 discloses catalysts containing essentially three compounds deriving from the following metals:
1. Copper, PA1 2. a metal selected from the metals of groups VI.sub.B, VII.sub.B and the non noble metals of group VIII, PA1 3. a metal selected from groups IV.sub.B and V.sub.B. PA1 1. cobalt, PA1 2. at least one metal selected from the group consisting of copper, silver, gallium, zirconium, zinc and thorium, PA1 3. at least one metal selected from the group consisting of palladium, platinum and nickel, and PA1 4. at least one alkali metal. PA1 1. Cu+Co+Zn+I.sub.A PA1 2. Cu+Co+Zn+Zr+I.sub.A PA1 3. Cu+Co+Zn+VIII noble metal+I.sub.A PA1 4. Cu+Co+Zn+Zr+rare earths+I.sub.A PA1 5. Cu+Co+Zn+Zr+rare earths+VIII noble metal+I.sub.A PA1 organic acids containing two or more acid groups, for example oxalic, malonic, succinic or glutaric acids, PA1 acid-alcohols, for example glycolic, lactic, malic, tartaric or preferably citric acids, PA1 amino acids, for example aminoacetic acid, alanine or leucine; alkanolamines, for example monoethanolamine, diethanolamine, triethanolamine, in a proportion of about 0.5 to 2COO.sup.- or &gt;--NH gram-equivalents per gram-equivalent of metals.
These catalysts also preferably contain 1 to 20% by weight of at least one alkali metal.
The European patent application No. 100,607 discloses catalysts containing at least four essential elements:
The alcohols obtained by the processes conducted in the presence of the above-mentioned catalysts have many applications. The high proportion of C.sub.2 -C.sub.6 alcohols thus obtained make advantageous the use of them in admixture with hydrocarbon cuts to form mixed hydrocarbon-alcohol motor-fuels.
As a matter of fact, the higher alcohols are more compatible with hydrocarbons than methanol; they also facilitate the incorporation of said methanol with hydrocarbons.
However, the processes for alcohol synthesis using the above-mentioned catalytic compositions generally suffer from various disadvantages:
The new catalysts according to the present invention only need to be conditioned under hydrogen and/or under reactive gases in a simple manner. Moreover, these new catalysts generally have a reducted transitory methanation, giving them a positive advantage in industrial use and exploitation security.